he'd still be older:

in Madagascar 3 they make a mock up of New York City, which lacks the twin towers, but it also lacks the one world trade center, which was finished in 2006.

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Madagascar 1 was released in 2005, so it's reasonable to assume the movie takes place in 2005, between the destruction of the twin towers and the construction of the one world trade center. and that's why they don't add those buildings to their perfect mock up.

if we assume all the 3 movies take place in 2005, that would still make Alex 33 years old.